Wanzhong Zhang

Reducing the cytotoxicity while improving the anti-cancer activity of silver nanoparticles through α-tocopherol succinate modification

By releasing Ag+ ions and generating reactive oxygen species (ROS), silver nanoparticles (Ag NPs) not only have good anti-tumor activity but also display cytotoxicity towards normal cells which limits their further application in the medical field. Up to now, there was still no appropriate method to reduce the cytotoxicity while improving the anti-cancer activity of Ag NPs. This paper focuses on counteracting the toxic side effect of the ROS from Ag NPs while simultaneously improving their anti-cancer effect. We used α-TOS to modify Ag NPs and investigated their bioactivity in vitro for the first time. The modified Ag NPs with a high α-TOS concentration not only show much higher anti-tumor activity than Ag NPs alone but also promote the survival of normal cell lines slightly, while the modified Ag NPs with a low α-TOS concentration display a lower cytotoxicity against normal cell lines without affecting their anti-cancer activity when compared to Ag NPs alone. Therefore, this work presents a higher potential for cancer treatment than using Ag NPs alone.

Silver nanoparticles with low cytotoxicity: controlled synthesis and surface modification with histidine

Due to the controlled release of Ag+, silver nanoparticles (AgNPs) not only display excellent anticancer activity but also possess cytotoxicity on normal cells. Up to now, no efficient method has been found to eliminate the side effect. In this study, AgNPs with different morphologies were synthesized and some main factors, i.e., the seed amount, CTAB concentration and temperature were discussed. Histidine (His) was applied to modify three kinds of AgNPs (near nanospheres, short nanorods and long nanorods) prepared by the above controlled synthesis, and the bioactivity of the modified AgNPs on cancer and normal cells was investigated. The results showed that the morphology and particle size of AgNPs had strong dependency on the quantity of seeds and reaction temperature except for CTAB concentration. IR spectra showed that His molecules had linked to AgNPs by coordination between AgNPs and C–N group of the imidazolyl in His. The bioactivity experiments in vitro showed that the cytotoxicity of His-modified AgNPs on HL7702 cells was effectively reduced and the anti-tumor activity against MCF-7 cells was not influenced obviously. The results supported that the His-modified AgNPs possess less cytotoxicity and higher targeting anticancer activity and thus the silver nanomaterials modified by His displayed potential applications for cancer therapies. We also suggested that the possible mechanism on the reduction of the cytotoxicity was that His-modified AgNPs could target cancer cells to decrease the cytotoxicity but affect a little on the viability of normal cells.

Preparation of triangular silver nanoplates by silver seeds capped with citrate-CTA+

Due to the competitive growth on the crystal face of seed, it is always difficult to control the morphology of the formation of nanoparticles precisely by a seed-mediated growth method. Herein, we provided a simple but effective technique to synthesize silver nanotriangles using a new silver seed that is capped with citrate-CTA+ (CTA+ is cetyltrimethyl ammonium cation). Compared to the preparation of silver nanoparticles (AgNPs) by a conventional seed-mediated method, in this paper, we presented a growth technique with two distinct innovative changes. First, the concentrations of CTAB that we added in silver seed collosol have a significant impact on the size distribution, and silver nanotriangles, nanorods, and nanospheres could be obtained by adjusting the CTAB concentration. Second, the seed prepared by our method has a longer use time, and silver nanotriangles, nanospheres, and nanorods could be prepared by adjusting the aged time of the seed colloid. We have also shown a simple way to control the morphology of silver nanoparticles in almost the same reactive medium by varying the NaOH concentration. Using the new silver seed capped with citrate-CTA+, we obtained triangular silver nanoparticles with relatively high regularity. Based on the limited experimental results and IR analysis, a possible mechanism was preliminarily proposed to explain the formation of the seed and the truncated triangular AgNPs.